1. Field of the Invention
The present invention relates to an image forming apparatus (electrophotographic apparatus), such as a printer, a copying machine, or a facsimile machine, and more particularly to an image forming apparatus characterized by a motor control technique for driving a toner bottle of the apparatus for rotation.
2. Description of the Related Art
Conventionally, a toner replenishment unit of an image forming apparatus for replenishing toner from a toner bottle is comprised of a motor (toner bottle motor) formed by a brush motor or a brushless motor, and a toner sensor in a sub hopper or a development device replenished with toner. Further, an image forming apparatus has also been proposed which is provided, to detect stoppage of tonner due to toner condensation, with a rotation detection unit for detecting rotation of a toner bottle or a stirring member (see Japanese Patent Laid-Open Publication No. 2001-356576).
In the image forming apparatus having the above-mentioned arrangement, toner is replenished from the toner bottle by rotating the toner bottle using the motor or rotating the stirring member in the toner bottle.
Further, if a sensor is provided in the toner bottle for detecting presence of toner, this complicates the construction and increases manufacturing costs. Therefore, the toner sensor is provided in the sub hopper or in the development device arranged within the main unit of the image forming apparatus.
Toner replenishment control is performed such that an image formation operation is stopped if it is detected that the toner is out, and after replacement of the toner bottle, the motor is rotated to continue a toner replenishing operation until it is detected by the toner sensor that the toner is present, whereafter the image formation operation is resumed.
Hereafter, a description will be given of the toner replenishment control periodically performed when the power is on and control for toner bottle replacement.
The toner sensor in the above-mentioned sub hopper detects whether or not toner is present, and if it is detected that the toner is present, the image forming apparatus is ready for image formation. If it is detected that the toner is out, the toner replenishment is performed by rotating the toner bottle or the stirring member in the toner bottle by the motor. While performing the toner replenishment, it is detected whether or not the toner is present.
If it continues to be detected that the toner is out in spite of continuing the toner replenishment for a predetermined time period, and further, if a toner sensor in the development device for detecting toner therein detects that the toner is out, the image formation operation is interrupted. Then, a replacement message or the like is displayed on a display section, for notifying the user that the toner in the toner bottle is out.
Thereafter, it is determined whether or not there is a possibility that the toner bottle has been replaced. This is carried out by detecting opening/closing of a door which is opened and closed when the toner bottle is replaced, using an opening/closing sensor. If it is determined that there is a possibility that the toner bottle has been replaced, the toner replenishing operation is started again.
The toner replenishing operation is continued until the toner sensor in the sub hopper detects that the toner is present, and when the toner sensor detects that the toner is present, the image formation operation is started again.
The image forming apparatus is controlled such that the image formation operation is not performed in a state in which the toner is out, by repeating the above-described sequence.
In a recovery operation for the above-described conventional image forming apparatus at the time of detecting that the toner is out, first, immediately after the toner sensor in the development device detects that the toner is out, the image formation operation is interrupted and an indication for toner replacement is displayed on the display section. Then, if a door-opening/closing operation is detected, the toner replenishing operation is started and continued until the toner sensor in the sub hopper detects that the toner is present. When the toner sensor detects that the toner is present, the image formation operation is started.
That is, when the user replaces the toner bottle, the image forming apparatus remains in a state in which the image formation operation is interrupted until the sub hopper is filled with the toner. This brings about a problem that it takes a long recovery time before the image formation operation is started after toner bottle replacement.